Automatic control of incident solar flux

ABSTRACT

Apparatus for automatic control of incident solar radiation consisting of transparent wall elements (2,3) and of opaque elements (7,8). The control is effected by reflection depending on the angle of incidence of the solar radiation. Single walled and multiple walled apparatuses are possible. In a simple two walled apparatus the opaque elements (7,8) are joined to two parallel wall elements (2,3) at an angle α, at least the wall element (2) directed towards the sun being translucent. The opaque elements (7,8) may be flat mirrors or mirrors of a particular shape. The specially shaped mirror sections (94,95) form radiation concentration and emission funnels, wherein absorber pipes may be provided in the radiation emission funnels. The two walled apparatus having flat reflective elements (7,8) between the wall elements (2,3) may be manufactured in a production line. Starting from the roll-off station (150,151,164) the reflective elements (7,8) and the wall elements (2,3) can be welded together and then cut into individual pieces.

This is a continuation of application Ser. No. 232,028, filed Feb. 2,1981 now abandoned.

AREA OF TECHNOLOGY OF THE INVENTION

The invention relates to an apparatus for automatic control of incidentsolar radiation, with essentially transparent wall elements andessentially opaque elements which are arranged horizontally along theirlong axis and are arranged at intervals from each other on the verticalaxis so that light emanating from any one opaque element is notreflected directly back to it by any other opaque element.

STATE OF THE ART

Venetian blinds for shading living areas are already known, consistingof several parallel slats arranged one above the other, and they may befixed in front of or behind a window. In order to allow the greatestpossible amount of daylight to enter the living area and at the sametime to prevent the eyes of the people in the room being dazzled, aspecial conformation of such venetian blinds has been proposed, whereinthe slats are provided with a metallic sheen on their upper sides andwith a light-absorbing material on their underneath sides, (U.S. Pat.No. 689,474). This configuration however enables undesirable radiationfrom a window to the interior space and vice versa.

Furthermore there is known a solar collector element for transformationof absorbed solar energy, wherein the absorption surface consists of avertical wall of parallel, aluminium slats arranged one above the other(German Offenlegungsschrift No. 2522154). These slats are arcuate inshape, so that all the reflected beams fall onto the closest adjacentslat at the time. Thereby all of the incident solar energy is directedonto the absorption surface. As this absorption surface is howeveropaque it cannot be used for light control.

From the previously lodged application German Offenlegungsschrift No.2807421, which is however not a prior publication, there is known adevice for controlling the climate in a closed space, including aso-called sun blind which reflects the greatest possible part of thesun's rays onto the interior wall of the space. This sun blind consistsof triangular elements arranged one above the other which reflect thelight towards the exterior when the angle of incidence of the solarradiation is high and when the angle of incidence of the solar radiationis low direct the light onto a narrow absorption surface. With thisdevice light cannot enter the room behind the sun blind. Moreover withthe elements arranged in the form of mirrors the light cannot beconcentrated onto the absorption surface by double reflection. Itfollows that only for a very limited range of the angle of incidence isradiation reflected onto the absorption surface, with the result thateven with diffuse radiation the room is inevitably darkened.

In another known cover for light admitting apertures, windows and thelike, at least partially opaque prism elements are provided on a steeplyupwardly inclined surface, wherein the opaque prism surfaces face downinto the area to be illuminated (German Offenlegungsschrift No.2615379). The opaque prism surfaces may be covered with absorptive orreflective coatings and may be located behind and/or in front of a glasswall. When they are located between two panes of glass the prisms areprotected from getting dirty, and so the prisms may be made fromextruded transparent plastics material. The choice of the angles of theprism surfaces to each other and relative to the horizontal or verticaldepends among other things on the critical angle determined according tothe geographical latitude. In summer the light falling at a very steepangle of incidence is redirected into the far side of the interiorspace, while the solar rays falling at a flat angle of incidence arereflected outside. This known form of protection can't be used forcooling in summer or for heating in winter.

Furthermore there is known an apparatus for controlling the passage ofheat and light radiation through apertures in buildings, which sets outto prevent the entry of heat from the outside in warm weather and toallow more heat to enter in cooler weather (German OffenlegungsschriftNo. 1906990). This apparatus, which permits exact focus onto the sun atazimuth, has tilting wave shaped members which are arranged verticallyin columns acting as reflectors and penetrating lamellas. The anglebetween the lamellas and the horizontal corresponds approximately to thelatitude at which the apparatus is to be installed. Manufacture of suchan apparatus is very expensive because numerous separate lamellas andtilting wave shaped members are required. A continuous manufacturingprocess is impossible. Moreover the lamellas cannot serve as staticstiffening elements for the glass walls in a wind.

Finally sandwich assemblies made of PVC or polymethylmethacrylate(=PMMA) used for glazing glass houses, industrial buildings and sportscomplexes, are known (cf. catalogue DD 4 UN 2 "DETALUX" of the Jan. 10th1978 and also catalogue DP 10 U of the Jan. 15th 1978 of Flachglas AG8510 Furth). These sandwich assemblies comprise two transparent sidewalls arranged in parallel and fitted with structures on their surfacesor colours, joined together by means of several bridge pieces which areperpendicular to the side walls. Structures on the surfaces orcolourings of this kind however do not provide any light control.

AIM OF THE INVENTION

The invention aims to provide an apparatus for automatic control ofincident solar radiation and also a method for the manufacture of thatapparatus, wherein the apparatus comprises several shading elementsarranged at intervals from each other in such a way that the area lyingbehind the shading elements at a predetermined angle of incidence isshaded and whereby manufacture of the apparatus can be carried outeconomically.

SOLUTION

The invention achieves its object by the following features:

(a) at least one side of the essentially opaque elements and/or themembers supporting them are joined to at least one of the essentiallytransparent wall elements, whereby the essentially opaque elementsand/or the members supporting them together with the essentiallytransparent wall elements form a cross-sectional area;

(b) the essentially opaque elements are reflective on at least onesurface facing the sun;

(c) the incident solar radiation can be directed through thecross-sectional area by means of double reflection.

The manufacture of this apparatus may be performed by first placing theessentially opaque elements and/or the members supporting them at apredetermined angle to the essentially transparent wall elements andthen joining them to the latter.

ADVANTAGES OF THE INVENTION

The invention controls incident solar radiation by allowing moreradiation through in winter than in summer, and this control is effectedby taking advantage of the differing angles of incidence of solarradiation. Special control mechanisms are rendered unnecessary thereby.The method of manufacture of the apparatus according to the inventionmakes on-line production simple without manual operations within theproduction process being necessary.

DESCRIPTION OF THE DRAWINGS

There are shown:

FIG. 1 a sandwich assembly with diagonally arranged reflective bridgepieces;

FIG. 2 the amount of incident solar radiation on a southerly aspect at50° latitude at 12 noon depending on the angle of incidence of radiationat the time of year;

FIG. 3a a folding blind with transparent and opaque elements arrangedone above the other;

FIG. 3b the opaque and transparent elements of the folding blind shownin FIG. 3a shown spread horizontally;

FIG. 4a a folding blind in which the bridge pieces are arranged betweentwo flexible side walls;

FIG. 4b the folding blind of FIG. 4a shown folded up;

FIG. 5 an apparatus for control of incident solar radiation with mirrorsections for concentrating light;

FIG. 6 an apparatus for control of incident solar radiation with mirrorsections and absorber pipes provided therein;

FIG. 7 an apparatus for control of incident solar radiation located on asloping roof;

FIG. 8 the concentration factor depending on the angle of incidence ofthe solar radiation at different times of the year at a particulargeographical place;

FIG. 9 a machine for manufacturing an apparatus according to theinvention;

FIG. 10 a cross-section through a folding blind while being folded up infolding means.

FIG. 1 shows a vertical section through a part of a sandwich assembly 1consisting of two parallel side walls 2,3 made of transparent materialand joined together by means of bridge pieces 4,5. The space between thetwo bridge pieces 4,5 is full of air or another gas; however it can alsobe evacuated. The sandwich assembly 1, which is located in front of aheat storing outer wall 6, can furthermore extend in either directionand contain additional bridge pieces, not shown in FIG. 1. Double sidedreflecting foils 7,8 are on the upper surfaces of bridge pieces 45,which are made of a transparent, preferably plastics, material. There isan absorbent coating 11 on wall 6, in front of which the sandwichassembly 1 is located. A wall like this is also called a trombe wall.Bridge pieces 4, and walls 2,3 include an angle α the size of which isdetermined according to the latitude taking into account the directionthe wall is facing and the climatic conditions prevailing where thesandwich assembly is being used. This angle α and the angle of incidentsolar radiation β are in fixed relationship and this will be more fullydiscussed later.

At the end or at the beginning of a heating period set by thegeographical location of the place currently in question, the followingcondition of incident radiation should apply: β=90°-α=2α, wherein tanβ'=tan β/cos K and K is the angle of azimuth and β is the angle ofelevation. The values of β and K are known and can be found in theliterature (Alador and Victor Olgyay: Solar Control and Shading Devices,University Press, N.J.; Mieczyslaw Twarowski: Sonne und Architektur,Callwey Verlag, Munchen 1962). When β=2α the sun is shiningperpendicularly down onto the reflecting foil 8, shown by light ray 12,and is reflected back by the latter into the direction of radiation.

If at the end of a heating period the angle of incidence of solarradiation is β>β₂ it can be seen that all the light falling onto themetal foil 8 is reflected outwards; the wall 6 or an area adjacent tothe side wall 3 thus remains completely shaded from the radiation.

For a time after the begining of the heating period the relationshipβ<β₂ applies as the angle of incidence of the radiation decreases. Onepart of the solar radiation then passes directly through the sandwichassembly 1 onto the coating 11 of the wall 6, whilst another part fallsonto the metal foil 8, from where it is reflected, partly directly ontothe coating 11 and partly by reflection from the lower side of the foil7. A further part is reflected back outwards by the foil 8. As the angleβ decreases the amount of light being reflected back decreases, whilstthe amount of light falling directly or indirectly onto the coating 11increases. When the angle of incidence of solar radiation β correspondsto the angle of the bridge piece α, as illustrated in FIG. 1 by the ray13, then with all the angles of incident radiation β<β₁ all the sunlightis radiated directly or by means of a single or second reflection fromthe metal foils 8,7 onto the coating 11. The angles β₂ and β₁ thusdefine the limits at which the coating 11 is either totally in shade orreceiving the entire radiation. The maximal interval a_(max) between thebridge pieces 4,5 is determined in such a way that the ray 12 fallsperpendicularly onto the end point of the metal foil 8 at the angle β₂where the foil 8 touches the side wall 3. Thus ray 12 defines the shadowline. If the length of the bridge piece 5 is taken as s, then for themaximal interval a_(max) between two bridge pieces 4,5 the relationshipis a_(max) =s/cos (90°-α)=s/sin β₂. For structural reasons or to achievebetter visual screening the interval between the bridge pieces may beless than a_(max).

In FIG. 2 the amount of incident solar radiation E onto the side wall 2or the side wall 3 as the case may be or onto coating 11 is shown. Thecurve 14 here shows the amount of incident solar radiation onto thecoating 11 whilst the curve 15 shows the amount of incident solarradiation onto the side wall 2. Beginning when the angle of radiation isβ₁ that is when β>β₁, an increase in the amount of radiation 16 from theside wall 3 by reflection is presented. When the angle of incidence ofradiation β=β₂ then side wall 3 is in total shade. In FIG. 2 βrepresents the angle of elevation of the sun at 50° latitude at 12 noonon a facade with a southerly aspect. It goes without saying that forother latitudes and other facades correspondingly altered curves willapply. To ascertain the actual amount of radiation the angle of the sunat azimuth should be taken into account. From FIG. 2 it can be seen thatthe sandwich assembly of FIG. 1, to the effect of which therepresentation of FIG. 2 is related, has a seasonal control effectwithout any further adjustment mechanisms being necessary. This controleffect is in agreement with the desired seasonal heating and coolingprocesses, that is to say in summer cooling takes place and in winterheating takes place. With the sandwich assembly 1 shown in FIG. 1temperature control effects for areas or radiation collectors areachieved in this way. Instead of an area behind the side wall 3 orinstead of the wall 6 as shown in FIG. 1, other elements can be providedas and when desired, making use of incident light, for examplephotographic elements, water storage devices or solar collectors. Thedoubly reflective metal foils 7,8 on the bridge pieces 4,5 may bereplaced by vaporised metal layers, of which the upper sides may bespecularly reflective, whereas the underneath sides may even bediffusely reflective. The sandwich assembly 1 is preferably used asglazing to admit light to an interior space, for glass houses,decorative facades, roofs and the like. However in principle it can alsobe placed behind or in front of the window of a living area. If it isplaced so that it admits light to an interior space the side wall 3 maybe coloured, so that the incident radiated light may be somewhatsoftened and also so that the solar energy radiating into the room fromthe side wall 3 may be used for heating purposes.

An apparatus particularly suitable for location on the side of aninterior space is shown in FIG. 3a.

There is shown here a folding blind 20 located behind a window 21 havingtwo panes of glass 22,23 forming an insulating medium. By flexibletapes, of which FIG. 3a only shows only the tape 24, the individualfolding elements of the blind 20 are folded in concert. These foldingelements have two surface parts 25,26 and 27,28 of equal size, joined attheir respective edges. The surface parts 26,28 have a rigid reflectiveelement 29,30 on their upper sides, and this element may suitablyconsist of a double-sided reflecting foil made of metal or plastics, ona translucent plastics foil 31,32, made for example of PVC, PE,Polyester or PP.

FIG. 3b, in which the surface areas 25-28 are shown in the unfoldedstate, shows this still more clearly. It can be seen that the softmembrane-like surface parts 25,27 and the plastics foils 31,32 togetherform one single piece of foil with the reflective surfaces 29,30 on it.Despite the fact that materials of different strength are used theindividual surface parts may be folded up very easily without breakingat the folds or without the reflective elements becoming crumpled. Theway the folding blind 20 works may be compared with the way the sandwichassembly 1 works. In both cases reflective surfaces are provided facingthe direction of the incident solar radiation, the surfaces beinglocated at an angle α depending on the angle of incidence of solarradiation β. In the case of the sandwich assembly 1 reflective metalfoils 7,8 are provided, whereas in the case of the folding blind 20 thereflective surfaces 29,30 are fuse-bonded. In both apparatuses aircurrents perpendicular to the main surfaces are cut off. The sun's rays33,34 falling at the angles β₁ and β₂ through the panes 22,23 arereflected by means of the folding blind 20 in the same way as they arereflected by the sandwich assembly 1. In contrast to the sandwichassembly the folding blind 20 has no parallel side walls between whichthe bridge pieces are rigidly attached, but the folding elements areheld together by the tapes 24 which have special attachments 35,36 onthem connected to the reflective elements 29,30. The radiation reflectedby means of the reflecting elements towards the interior area is eitherreflected onto the ceiling of the interior area not shown in FIG. 3a oronto the underneath side of the upper reflector 29, from where it getsinto the interior space in the form of light or heat radiation 37. Theunderneath sides of the reflective layers 29,30 may also be colouredwith a colour which will absorb a certain amount of light so that thesecoloured reflectors 29,30 may be cooled by convection currents and byreflecting heat into the interior space. In addition the surface part 27may also be coloured, for example it may be gold. In FIG. 4a a furtherfolding blind 40 is shown differing from the folding blind 20 of FIG. 3aessentially in that its reflective elements are not connected to onlyone transparent foil, but are located between two different transparentfoils.

The film 41 facing the sun 39 and the film 42 facing the interior spaceconsist of flexible and transparent material, of which the film 42 maybe coloured. Between these films 41,42 the bridge pieces 43,44,45, whichare reflective on both sides, are inclined at an angle α, having thesame relationships to the angle of incidence of solar radiation β ashave already been described in connection with FIGS. 1 and 3a. In thedouble walled folding blind 40 the connections between the films 41,42and the bridge pieces 43, 44,45 are effected by gluing or welding stripshaped areas 49,54 of the films to the bridge pieces 43,44,45 to formhollow spaces 46,47,48.

In FIG. 4b there is shown a way of manufacturing the blind 40 asdepicted in FIG. 4a by means of folding. To this end a three layeredsandwich element 55 is formed having the reflective bridge pieces43,44,45 in the middle and having outer layers consisting of films41,42. The bridge pieces 43,44,45 are glued or welded to the films 41,42at points 55-60, and this can be done in a continuously operatingproduction line situation. Alternatively the bridge pieces 43,44,45 mayalso be joined to the films 41,42 at their edges.

In FIG. 5 there is shown a further apparatus for automatic control ofincident solar radiation having two semi-transparent wall elements 61,62and several opaque mirror sections 63,64 located one above the other,and concentrating the solar radiation. These mirror sections 63,64consist of three surfaces 65,66,67 and 68,69,70 as the case may be.Positive connections between the mirror sections 63,64 and wall elements61,62 are made by fitting each of specially shaped projections71,72,73,74 on the walls element's into its corresponding recess75,76,77,78. As the projections 71,72,73,74 are so fitted the wholething is assembled. The wall element 61 is exposed to direct solarradiation, whilst the wall element 62 is in shadow. The arrangement oftwo mirror sections above or below each other as the case may be definesan inlet cross-section 79, a concentration cross-section 79.1 and alsoan emission cross-section 80. The trough-shaped intake funnel is definedby the reflective area 66 and the reflective partial area 81. Thereflective area 66 is parabolic in shape with its focus F at the end ofthe partial area 81 opposite it within the concentration cross-section79.1. The axis 82 of the parabola indicated through the area 66 isinclined at an angle β, corresponding to the lowest angle of incidenceof solar radiation β_(min) to be trapped. The opposite side wall 81 isplanar in form, however it may also be in the shape of a parabolic curveor of some other shape. Adjacent to the planar partial area 81 is acircular surface 83, whose centre M lies at the end point of theparabolic surface 66 in the concentration cross section K. The light isdirected by this surface 83 into an emission funnel 84. The radiationfalling onto the surface 67 is dispersed into the space behind the wallelement 62, so that the radiant energy falling upon any collectors thereis likewise unfocussed. Accumulation of heat in the region ofconcentrated radiation energy is thus avoided. The surface 67 acts as areflector for a part of the radiation being reflected off the wallelement 62 or off the absorber surface 86. The wall element 62, which byway of example may consist of glass, principally reflects a part of thelight directed to it. As the surface 67 and the wall element 62 enclosea wedge-shaped space, the fraction of the light reflected by the wallelement 62 onto the surface 67 is reflected back and forth several timesbetween the surface 67 and the wall element 62, with the result that allthe radiation directed by the concentrator onto the emission funnel 84penetrates the wall element 62 without reflection losses. This permitsthe absorption surface 86 to have a smaller co-efficient of absorption,as the radiation reflected back by the surface 86 into the emissionfunnel 84 is radiated back onto the absorption surface 86. As theco-efficient of emission is the same as the co-efficient of absorption,the emission of a collector surface may be reduced with the aid of suchan emission funnel 84 by lowering the absorption capacity when theco-efficient of total absorption is the same or higher. The shape of theemission funnel 84 also makes it possible to have several sheets ofglass on the side of the interior space without loss of energy radiationas a result of reflection. Furthermore it is possible to put a heatmirror 86.1 on the side of the interior space on a foil 85. Heat mirrorsof that kind, which for example can also serve as sun shields, are madeby metallic vaporising processes known in themselves (Compare GermanOffenlegungsschrift No. 2238355) and usually also are capable ofreflecting visible rays. The reflected part of the radiation is howeverreflected again by the multi-reflections in the emission funnel 84 withthe result that loss of radiation is avoided despite the reflectingeffect. The emission funnel 84 thus makes possible a high degree ofenergy gain and heat storage, which is why the apparatus shown in FIG. 5is particularly suitable as a facade element for a light absorbing andheat storing wall.

The apparatus of FIG. 5 can also be enclosed in a framework 87 securedto an outer wall 88. The apparatus is possibly connected to the frame 87by means of a rigid section 89. The transparent foil 85 is glued in agroove 90. The frame 87 may be an extruded PVC section with an aluminiumsection 91 inserted into it for stiffening. A special sealing lip 87.1is provided on the wall element 61 to seal the frame 87.

In FIG. 6 there is shown a further apparatus for automatic control ofincident solar radiation, comprising two transparent wall elements 92,93between which mirror sections 94,95 are located. The apparatus is joinedto an external wall 97 by means of a batten 96 acting as a support, withthe result that special frame pieces are to a large extent renderedunnecessary. In this way the apparatus can be made to suit the style ofthe building where it is to be erected and desired dimensions may beobtained. Parabolic areas 98,100 and also areas 99,100 facing towardsthe interior area are mirrored on the surfaces facing towards theincident radiation on the mirror sections 94,95. Opposite the elements98,99; 100,101 there may be an arcuate surface area 102,103. At thefocus of the areas 99,100 there is an energy collector 104,105, takingthe form of an absorber pipe with a heat transfer medium flowing throughit. Because of the special configuration of the sections 94,95 theseenergy collectors 104,105 receive a constant amount of radiant energylargely irrespective of the angle of the sun according to the season ofthe year, whilst the amount of radiation on the wall element 93decreases as the angle of the sun increases. In this way the desiredautomatic control effect with respect to the "heating" or "cooling"function is achieved. As a result of the location of the energyreceivers 104,105 the cosine losses are used in such a way that thesolar heating of the building or of the wall as the case may beautomatically cuts out when the angle of radiation is great.

Of particular advantage is the circumstance that the energy receivers104,105 on the one hand are located on the side of the mirror sectionsfacing the interior space and on the other hand are covered from aboveby the curve of the parabolic profile sections 99,101. In this way theheat accumulates on the side of the interior space and cannot flow awayto the irradiated side.

Focus points F₂ and F₃ as the case may be of the parabolic profiledelements 98,100 are right on the transparent wall element 92 and formthe exit point for a circular mirror surface, formed by the profiledelements 102,103. The mirror surface is thus defined by the centrepoints M₂, M₃ at the end point of the parabolic surfaces 98, 100 andalso by the concentration cross section regions K₁,K₂. The profiledelements 99,101 on the shaded side which curve around the absorber pipes104,105 are empirically chosen so that the desired dispersion of theradiation relative to the varying angles of the sun occurs. The curve ofthe elements 99,101 thus achieved is parabolic. In FIG. 6 the path ofthe rays at angle β₁ and angle β₂ is shown, which clarifies the opticalautomatic control effect. The ray 106 at angle β₂ is thus directed ontothe absorber pipe 105, whilst the ray 107 at angle β₁ is beamed throughthe wall section 93 after it has been reflected four times. The opaqueelements 94,95 are linked by two parts 108,109 which may suitably bemade of foamed polyurethane or polyisocyanurate.

The apparatus is mounted on the batten 96 to which the wall elements 92are screwed and set. The absorber pipes 104,105 are then placed inposition. In a further process the parts 108,109 are attached to a lug110 in the wall element 93 and covered by the wall element 92. The outerwall element 92 is assembled from the bottom to the top, by fitting eachlower surface 111 into its respective saw-toothed shaped detent 112. Theupper surface 113 is joined to the lower surface of wall element 92 bymeans of a joint wherein two U-shaped connections 114,115 are fitted oneinto the other. This connection is of such a shape that the lower Uconnection 115 forms a gutter for the condensation running down fromabove. The outer edges of the U connections 114,115 are notched inplaces to enable condensation to run off. In FIG. 7 a further apparatusfor control of the light radiation is shown, which is used preferably onsteep roofs of dwellings and glass houses and other structures or as adecking. The purpose of this apparatus is, among other things, toprovide concentration of the solar radiation, as for example is morefully expounded in German Offenlegungsschrift No. 28 23 252. Theapparatus has two transparent wall elements 116,117, between which thereare several opaque and reflective sections 118,119. By means of twosections 118,119 one radiation intake funnel 120,122 is formed with aradiation emission funnel 121,123 joined to it. The radiation intakefunnel 120,122 is thus formed by two opposed parabolic parts 124,125 and126,127 as the case may be, one of those parabolic parts 125,127 beingessentially smaller than the other parabolic 124,126.

The entire apparatus is located above a decking 128 with an absorbersurface 129 on it. Above the absorber surface 129 there are a first foil130 and a second foil 131 serving as heat shields. Parallel to thesecond foil 131 the wall element 117 is located, which is reflective atpredetermined points 132,133,134 on its underneath side. The radiationemission funnel 121,123 is in the shape of a parabola and fulfils therequirement that each ray 135 reflected from the radiation transmissivesurface 117 is reflected back at least once onto the radiationtransmissive surface 117. In the same way the light rays 136 and 137which are reflected off the foils 130, 131 are reflected back by theradiation emission funnel 121,123 or the reflecting zone 133. Theabsorber 129 is a storage collector element on a decking 128, theapparatus being located some distance above it. The radiation emissionfunnel 121,123 fulfils the previously given condition when the wallelement 117 is located perpendicular to the axis of the parabola, andwhen the focus F₅ lies at the end point of the mirror surface where theconcentration cross section also is to be found. In winter, when theangle of radiation is small, light is let through by the apparatus shownin FIG. 7, whilst in summer it casts a shadow.

In FIG. 8 this connection is shown once again for latitude 50° at 12noon. From curve 138 it can be seen that the concentration factor C_(F)depends on the angle of radiation and thus on the time of year, shown by21.12, 21.3, 21.9, 21.6. The chopping off of the curve in the region 139is brought about by the continually increasing radiation, being radiatedback from the region 140 between the points 141,142. A particularlylarge factor of concentration during winter and when the radiation angleis small is thus achieved by means of the region 140. The radiationreflected back in the region 140 falls at a very flat angle onto theouter wall element 116. This angle is designated α in FIG. 7.Corresponding to this flat angle of radiation the fraction of theradiation reflected off the wall element 116 is very high, with theresult that radiation back into the concentration funnel is achieved.The actual concentration factor thus follows the curve parts 143,144.

The external wall element 116 may be in the form of a prism, whereininternal reflection of the beam of light from the side wall element 140extends over a greater arc of the angle. The prism shape is thentapered, as indicated by the broken line 116.1.

Solar cells may be moulded into the wall element 117. In that case theparabolic shape of the radiation emission funnel 121,123 is especiallyadvantageous, because reflective elements are as a rule located betweenthe individual solar cell chips. The radiation falling onto the chips isreflected back from the said reflector elements into the radiationemission funnel 121,123 and beamed back thence onto the chips.

At this point attention is drawn to the fact that the mirror sectionsdescribed herein are given by way of example only. Other mirrorsections, such for example as those described in German patentapplication No. P29 42 497.3, may likewise be used.

In FIG. 9 a possible method of manufacture of the apparatus according toFIG. 1 is shown. In the manufacture of such apparatuses the transparentwall elements 2,3 are wound off the rollers 150,151 in the form ofsheets of plastics and are carried via the diverting rollers 150.1,151.1 to the welding stations 154, 155 and are welded onto the sideedges of the transverse bridge pieces. The said transverse bridge piecesare in sheet form at first and are wound off a wind-off roller 164. Asthe transverse bridge pieces are at a predetermined angle α to the wallelement the plastics strips 156,163 which have already been madereflective are turned into the required positions. Two guide rolls170,171 aid in positioning the sheets 156-163. Guide elements not shownin the Figure are located between the plastics sheets or bridge pieces156-163, said elements preventing uncontrolled sideways movement of thebridge surfaces under the stress of the welding step which is done withsonotrodes. Having been welded together, the individual parts are nowseized and drawn away by means of a conveyor 172,173, the conveyorconsisting of an endless belt 174,175 and two cylindrical rollers176,177; 178,179.

In cases where the sandwich assemblies manufactured by the mechanismillustrated in FIG. 9 are rigid, the individual plates behind theconveyors 172,173 are cut off by means of a cross cutter. On the otherhand if they are flexible and intended for a folding blind they can befolded up by means of the guide rails 180-187 and cut to length by aroll press with rolls 188,189 on it by means of a cross cutter 190.

To stretch the edges of the blind while it is being folded withoutpulling it out of shape the edges of the blind are heated, for example,and as a result of temperature-induced spreading the desired extensivelengthening of the outer parts of the blind becomes possible. Instead ofthe guide rails 180-187 guide rollers may also be used, the said rollerspressing onto the folds, thus folding the blind up. The transparent wallelements 2,3 or the plastics sheets 152,153 as the case may be can alsobe laminated foils and, by way of example, may be in the form of twodifferent layers, one layer being particularly adapted as a carrier andmade for example of PVC, the other layer being particularly resistant toUV light. The bridge pieces may also be be made of such laminated foils.

The side edges may be chamfered to enable better welding of thetransverse bridge pieces to the wall elements.

When a=s manufacture of the two piece assembly is particularly simple.

It should be borne in mind that the sheets 156-163 are alreadyreflective before they are joined to the wall elements; that is to say,as a rule, reflective sheets are wound off the roller 164. At any rateit is not necessary to put completed sheets in their final form onto theroller; rather, it would also be possible not to separate a plasticssheet previously made reflective into several smaller strips by means ofa lengthwise cutter until after it leaves the roller 164.

FIG. 10 shows cutting of a folding blind 191 during the folding step.Here, the side walls 192,193 are kinked inwards between the bridgepieces 194,195,196, with the result that folding occurs along the axis197.

I claim:
 1. Apparatus for control of incident solar radiation,comprising essentially opaque elements (63, 64; 108, 109; 118, 119),which are arranged horizontally along their axis and are at intervalsfrom each other along a vertical axis, each opaque element having areflectng upper surface and reflecting lower surface wherein thereflective upper surface opaque element lies opposite the lower surfaceof the next adjacemt element, and the lower surface of the next adjacentelement lies opposite the upper surface of a second adjacent element,thus admitting radiation between the upper surface of said opaqueelement and the lower of the adjacent element, characterized by thefollowing chracteristics:each of the opaque elements is formed as aprofile (63, 64; 108, 109; 118, 119) having mirror like surfaces; theupper and lower surfaces of each opaque element (63, 64; 108, 109; 118,119) are different in shape; at least one portion of the lower surfaces(63, 69) of said mirror-profile is parabolic; the upper and lowersurfaces of said mirror-profile established a radiation cross-section aswell as a concentration cross-section (K, K₁, K₂); and the opaqueelements (63, 64; 108, 109; 118, 119) are provided in between panel-liketransparent elements (61, 62; 92, 93; 116, 117); whereby light reflectedto an exterior of said apparatus is scattered by double reflection onthe different contours of said upper and lower surfaces of said opaqueelements.
 2. Apparatus according to claim 1 characterized in that theupper surface of an essentially opaque element (119), has at least part(126), wherein the said part is parabolic in shape and the focus of thepart (126) is located in the concentration cross-section, and in thatthe lower side of an essentially opaque element (119) consists of atleast two parts (123, 125) wherein the one part (125) extends from theradiation inlet cross-section to the concentration cross-section in thesecond part (123) leaves from the concentration cross-section to theirradiation cross-section.
 3. Apparatus according to claim 1,characterised in that the essentially transparent wall elements (61,62;92,93; 116,117) are in the shape of prisms.
 4. Apparatus for control ofincident solar radiation, comprising a essentially opaque elements (63,64; 108, 109; 118, 119), which are arranged horizontally along theiraxis and are at intervals from each other along a vertical axis, eachopaque element haivng a reflecting upper surface and a reflecting lower,surface wherein the reflective upper surface opaque element liesopposite the lower surface of the next adjacent element, and the lowersurface of the next adjacent element lies opposite the upper surace of asecond adjacent element, thus admitting radiation between the uppersurface of said opaque element and the lower of the adjacent elementcharacterized by the following characteristics:each of the opaqueelements is formed as a profile (63, 64; 108, 109; 118, 119) havingmirror-like surfaces; the upper and lower surfaces of each opaqueelement (63, 64; 108, 109; 118, 119) are different in shape; at leastone portion of the lower surfaces (63, 69) of said mirror-profile isparabolic; the upper and lower surfaces of said mirror-profile establisha radiation cross-section as well as a concentration cross-section (K,K₁, K₂); the opaque elements (63, 64; 108, 109; 118, 119) are providedin between panel-like transparent elements (61, 62; 92, 93; 116, 117);the upper surface of an essentially opaque element (119) has at leastone part (126), wherein the set part is parabolic in shape and the focusof the part (126) is located in the concentration cross-section; thelower side of an essentially opaque element (119) consists of at leasttwo parts (123, 125) wherein the one part (125) extends from theradiation inlet cross-section to the concentration cross-section and thesecond part (123) leads from the concentration cross-section to theradiation cross-section; the upper surface of one essentially opaqueelement (63, 64; 108, 109; 118, 119), has at least one part (65, 68;102, 103) extending from the concentration cross-section (K) to theemission cross-section (80, 93); the said part (65, 68; 102, 103) hasone surface which is shaped like the jacket of a cylinder with amidpoint (A) located in the concentration cross-section; the lowersurface of an essentially opaque element (63, 64; 108, 109; 118, 119)consists of at least one part shaped like a parabola wherein the focusof the parabola (F₁ -F₃) is located in the concentration cross-sectionof the upper surface of an adjacent element; and the end point of theparabolic part in the concentration cross-section forms the midpoint (M)of the surface shaped like the jacket of a cylinder of the upper surfaceof an adjacent element.
 5. An apparatus for automatic control ofincident radiation with transparent wall elements (61, 62; 92, 93, 116,117) and opaque elements (63, 64; 108, 109; 118, 119) which are arrangedin parallel and having a distance from each other, said opaque elements(63, 64; 108, 109; 118, 119) being arranged and continuously extendingbetween the transparent wall elements (61), 62; 92, 93; 116, 117) andhaving at least a reflecting area directed to the incident radiationwherein two opaque elements (63, 64; 108, 109; 118, 119) form in aradiation section and an emission section characterized in that saidapparatus for automatic control of incident radiation is locatedvertically or at an angle to function as a separating and heatinsulating wall between an interior and an exterior space, and in that awall is built within a framework or built up from separate sections andmounted as a facade on a support, the upper surface of a first opaqueelement (81, 83) and the lower surface of a second opaque element (66,67) form a concentration section (K) which is located between theradiation section and the emission section wherein the contour of theupper surface of an opaque element (63, 64; 108, 109; 118, 119) differsfrom the contour of the lower surface of said opaque elements (63, 64;108, 109; 118, 119).
 6. An apparatus for automatic control of incidentradiation with transparent wall elements (61, 62; 92, 93; 116, 117) andopaque elements (63, 64; 108, 109; 118, 119) which are arranged inparallel and having a distance from each other, said opaque elements(63, 64; 108, 109; 118, 119) being arranged and continuously extendingbetween the transparent wall elements (61, 62; 92, 93; 116, 117) andhaving at least a reflecting area directed to the incident radiationwherein two opaque elements (63, 64; 108, 109; 118, 119) form in aradiation section and an emission section characterized in that thetransparent wall element (61, 62; 92, 93; 116, 117) and the essentiallyopaque elements (63, 64; 108, 109; 118, 119) are extruded from plasticmaterial and assembled into a wall-like structure by means ofinterlocking and snap fitting fastening, the upper surface of a firstopaque element (81, 83) and the lower surface of a second opaque element(66, 67) form a concentration section (K) which is located between theradiation section and the emission section wherein the contour of theupper surface of an opaque element (63, 64; 108, 109; 118, 119) differsfrom the contour of the lower surface of said opaque elements (63, 64;108, 109; 118, 119).
 7. An apparatus for automatic control of incidentradiation with transparent wall elements (61, 62; 92, 93; 116, 117) andopaque elements (63, 64; 108, 109; 118, 119) which are arranged inparallel and having a distance from each other, said opaque elements(63, 64; 108, 109; 118, 119) being arranged and continuously extendingbetween the transparent wall elements (61, 62; 92, 93; 116, 117) andhaving at least a reflecting area directed to the incident radiationwherein two opaque elements (63, 64; 108, 190; 118, 119) form in aradiation section and an emission section characterized in that theupper surface of a first opaque element (81, 83) and the lower surfacesof a second opaque element (66, 67) form a concentration section (K)which is located between the radiation section and the emission sectionwherein the contour of the upper surface of an opaque element (63, 64;108, 109; 118, 119) differs from the contour of the lower surface ofsaid opaque elements (63, 64; 108, 109; 118, 119) and the upper surfaceof said first opaque element and lower surface of said second opaqueelement establish a sluice for radiation at the one side of whichradiation can enter whereas the other radiation can leave.
 8. Apparatusaccording to claim 7, charcterized in that at least one energytransformer is provided within the mirror system, said energytransformer transforming the optical energy into another form of energyand the energy transformer is an absorber pipe or the like and isprovided in the region of the lower surface of the essentially opaqueelement (63, 63; 108, 109; 118, 119), and also behind the concentrationcross-section on the inner side in the region of the radiationcross-section.
 9. Apparatus according to claim 7, characterised in thatthe irradiation cross-section (80) of the light radiation sluice islarger than the concentration cross-section.
 10. An apparatus forautomatic control of incident radiation with transparent wall elements(61, 62; 92, 93; 116, 117) and opaque elements (63, 64; 108, 109; 118,119) which are arranged in parallel and having a distance from eachother, said opaque elements (63, 64; 108, 109; 118, 119) being arrangedand continuously extending between the transparent wall elements (61,62; 92, 93; 116, 117) and having at least a reflecting area directed tothe incident radiation wherein two opaque elements (63, 64; 108, 190;118, 190) form in a radiation section and an emission sectioncharacterized in that the upper surface of a first opaque element(81,83) and the lower surface of a second opaque e1ement (66, 67) form aconcentration section (K) which is located between the radiation sectionand the emission section wherein the contour of the upper surface of anopaque element (63, 64; 108, 109; 118, 119) differs from the contour ofthe lower surface of said opaque element (63, 64; 108, 109; 118, 119),the opaque elements are made from plastic by expanding the plastic intoa mold cavity whose internal dimensins correspond to the externaldimensions of the opaque elements to make a hollow piece and foaming thehollow piece.
 11. An apparatus, according to claim 10 wherein the opaqueelements further include a metalized foil which is added to the opaqueelements by providing the metalized foil in the mold cavity before theplastic is expanded and foamed.
 12. Apparatus according to claim 10,characterised in that the light entering through said radiation-sectionwhen at one angle of incidence shines into a concentration section, andin that the said angle of incidence increases as the angles of elevationβ of the sun decrease, whereby when the angles of elevation β aresmaller higher concentration factors may be achieved, and when theangles of elevation β are greater smaller factors of concentration maybe achieved or shading of the concentration or radiation section may beachieved.
 13. Apparatus according to claim 10, characterised in that theupper surface of an essentially opaque element 63,64; 108,109; 118,119),consists of at least two parts, wherein the first part (81, 75) is onewall element of a radiation concentration funnel, and extends from theradiation section (79) to the concentration section (K), and wherein thesecond part extends from the concentration section (K), as far as theradiations section.
 14. Apparatus for automatic control of incidentradiation with transparent wall elements (61, 62; 92, 93; 116, 117) andthe opaque elements (63, 64; 108, 109; 118, 119) which are arranged inparallel and having a distance from each other, said opaque elements(63, 64; 109; 118, 119) being arranged between the transparent wallelements (61, 62; 92, 93; 116, 117) and having at least a reflectingarea directed to the incident radiation, wherein two opaque elements(63, 64; 108, 109; 118, 119) form an irradiation section and an emissionsection characterized in that the transparent wall elements (61, 62; 92,93; 116, 117) are made by:rolling off a first sheet of material (153)from a first roll off station; rolling off a second sheet of material(152) from a second roll off station syncronously with the first sheetof material (153); rolling of strips of material (156 through 163) froma third roll off station (164) synchronously with the first and secondsheets of material (152, 153) and positioned at a predetermined angle tosaid first and second sheets of material (152, 153); joining the stripsof material (156 through 163) to the first and second sheets of material(152, 153); and cutting the strips of material (156 through 163) and thefirst and second sheets of material (152, 153) joined to them to lengthby cutting devices.
 15. An appaatus for automatic control of incidentlight, comprising transparent wall elements spaced from each other,opaque elements which are arranged in parallel, spaced from one another,located between the transparent wall elements and have at least areflecting area facing the irradiated light and wherein two opaqueelements form an irradiation section and an emission section, the uppersurface of a first opaque element and the lower surface of a secondopaque element form a concentrated section which is located between theirradiation and emission section, the upper surface of an opaque elementdiffers from the contour of the lower surface of said element, theopaque elements continuously extend from a first transparent wallelement to a second transparent wall element, all of the opaque elementsare formed with a profile which is unsymmetrical in section with respectto an axis parallel to the transparent wall and with respect to an axisvertical to said transparent walls with said profile sections having allthe same shape so that the concentrating sections between the opaqueelements are all identical, at least one side of the opaque elementscomprise a concave mirror, at least one side of the opaque elementscomprise a reflector directed to the inner room and a reflector directedto the outer room and the volume between one of the concentratingsections and the transparent wall element located at the irradiationsection is greater than the volume between said concentrating sectionand the transparent wall element located at the emission section.